1. Field of the Invention
The present invention generally relates to the gain control of a wireless transmitter. More specifically, the present invention provides a wireless transmitter having an extended gain control with improved local oscillator (LO) leakage rejection.
2. Background Art
A wireless transmitter uses gain control to efficiently transmit signals. Properly setting an output power of a transmitted signal conserves battery power and prevents the transmitted signal from interfering with other wireless transmitters.
Often, the gain of a wireless transmitter is implemented in two stages. A first gain stage provides a programmable or variable gain. A second gain stage provides a fixed or constant gain. As a result, the range of the gain is limited by the variable gain of the first gain stage. Further, if the first and second gain stages are implemented after up-conversion of the output signal to a radio frequency, the fixed gain of the second gain stage renders the wireless transmitter susceptible to LO leakage interference.